A. Field of the Invention
The present invention relates to a guide tube assembly for an endoscope or more particularly, to a assembly which is usually flexible, which can be stiffened when necessary.
B. Description of the Prior Art
An endoscope is an optical instrument which utilizes flexible optical bundles and a flexible sheath for inspecting a body cavity or a reactor pile. When inserting the forward end and the sheath into the cavity, it is desirable that the forward end and the sheath be freely curved so that these portions can pass through the circuitous passages of the body cavity and the reactor pile. It is preferable that the forward end be fixed firmly when conducting an inspection of an object to be observed because the stable image of the object can be transmitted by the endoscope. It is desired that such a fixing function is assigned to the guide tube assembly which is used with the endoscope rather than assigning the function to the endoscope itself, because the construction of the endoscope can be simplified. In addition, such a guide tube assembly can prevent the wall of the body cavity from injury. But, such a guide tube assembly with the ability to fix the forward end has not yet been developed.